[fmihaila]

> I have yet to see a feature only moat.

Features that induce a significant network effect can potentially lead to a moat. No contracts necessary.

(Maybe this is what you meant when you mentioned "size" as a moat-building mechanism.)

[ehnto]

Yep, that was the intent behind mentioning size. Google could be said to have a network effect based moat around Google Docs for example.